December 1996, Volume 5, Number 4
This paper deals with design of wideband low-noise preamplifier of atmospheric optical link receiver. Sources of noise and the noise models for the PIN photodiode coupled to a transimpedance amplifier are described here. This paper presents the way of optimization the signal to noise ratio at the required frequency range.
I present one of the methods of assessment of accuracy and resistance to interference of a distance -measuring channel of radionavigation system of near-navigation. By using computer technology, the method enables us to determine the potential but also the real error measuring the distance of the flying object by radionavigation distance meter.
Two different hand-held phones operating at 1.8 GHz are numerically analyzed, applying a field calculation program MAFIA (MAxwell's equations using the Finite Integration Algorithm). One phone contains a Back-Mounted Microstrip Double Patch Antenna (BMMDPA), the other, for comparison a conventional monopole. Realistic models of the the handset, the head and the hand are used to gain a detailed understanding of the antenna properties, as well as of the antenna-tissue interaction.
A novel method for vector scattering parameter measurement is presented. The method is based on scalar (SWR) measurement only. Vector data is obtained using a controlled perturbation two-port (CPTP). The method promises broadband operation and cost-effectiveness for both reflection and transmission measurements. Design considerations for CPTP synthesis are presented.
In some instruments oscillator with precision 90° phase shift of output signals is needed. In this article a new type of RC oscillators with precision 90° phase shift between two low impedance output signals is described. This phase shift does not depend on tolerances of RC networks used.
The paper presents the results of a study on the use of invertible rapid transform for the motion estimation in a sequence of images. Novel motion estimation algorithms based on the analysis of the matrix of states (or matrices of states) of the invertible rapid transform are described. Experimental results with proposed algorithms are presented and compared with the well-known 2D-log method in real image sequences.